For almost all of their existence as a separate species, humans have lived in relatively isolated groups (“hunting-gathering camps”) of ten to forty people. See Tuck, Edward F. and Earle, Timothy “Why CEOs Succeed and Why They Fail,” published in Strategy and Business, Issue 5 (Fourth Quarter 1996). The group behaviors of humans, and their bodies and senses, have evolved to fit this manner of living.
All animals, including insects and bacteria, and many plants, have some means of communicating with others of their species. The most common means use the chemical senses: taste and smell. Some of the substances that activate these senses for information transfer are called “pheromones.” A pheromone is defined in the Merriam-Webster Office Dictionary as “a chemical substance that is produced by an animal and serves especially as a stimulus to other individuals of the same species for one or more behavioral responses.”
Some pheromones are sexual attractants. However, mammals, including humans, use odors other than pheromones to provide far more detailed information. Researchers found in 1982 that some mammals select their mates on the basis of a complementary Major Histocompatibility Complex (MHC) defined in the Merriam-Webster Office Dictionary as: “A group of genes in mammals that function especially in determining the Histocompatibility antigens found on cell surfaces.” The MHC contributes to the mammal's personal smell and uniquely identifies it, as well as carrying information on the mammal's immune system. Mate selection based on complementary MHC maximizes a mated pair's offspring's number of immune system responses, making for more disease-resistant, thus fitter, offspring; and, because mammals with different MHCs are not closely related, selection based on these criteria also avoids the hazards of consanguinity, which amplifies genetic defects. This is analogous to the human taboo against marrying one's close relatives.
For the original work on MHC mate selection among mammals, see Boyse EA et al., “Chemosensory Communication—A New Aspect of the Major Histocompatibility Complex and Other Genes in the Mouse,” Journal of Oncodevelopmental Biology and Medicine, Vol. 4 No 1-2: pages 101-116, 1982. Later work, in 1995, showed that women also select their preferred mates on this basis, but because of humans' relatively poor sense of smell, this selection must be done at very close range. See Wedekind C., et al., “MHC-Dependent Mate Preferences in Humans,” Proceedings of the Royal Society B, 260, pages 245-249, 1995.
Odors carrying information on MHC are produced in the skin or passed along in breath or urine. The sense of smell in free-ranging mammals is exquisitely sensitive and complex: it can identify a range of odors far greater than that needed to avoid danger and seek food. The major use of this enhanced sense is to detect and understand pheromones and to analyze the MHCs of others of its own species. To understand the profound importance of smell one must know that the first organ to evolve after the spinal cord was the olfactory bulb at its end. The rest of a chordate's brain evolved from this base (vertebrates, including mammals, are among the members of the phylum Chordata).
Unlike most mammals, humans and some apes have poor senses of smell. They have retained their ability to detect and analyze MHC; however, these odors can be detected and analyzed only at very close range. Our impaired sense of smell may be the result of the natural selection that took place in three million years of living in small camps (as discussed above), because it was no longer needed (women do not have a pronounced estrus cycle like most mammals. They are always receptive, and thus have no need to signal their receptiveness. Degrees of consanguinity are public information in a small group. Camp dwellers usually find their mates in neighboring camps, which provides genetic separation. Because they are usually in sight of one another, camp dwellers have no need for odors to advertise their gender, pregnancy, age, state of health and other visible features; humans in committed relationships often adorn themselves with special marks, such as wedding rings, tattoos, hair length and special clothing; information on mood, such as fear, is easy to gain from the context of a person's actions.)
In addition, pheromones in particular may have been detrimental to the fitness of the camp (constant reminders of sex are distracting and lead to jealousy and strife, which is deadly in a confined group; animals with strong odors are at more risk of predation.)
Between 10,000 and 100,000 years ago, depending on the society, most hunting-gathering camps combined into either pastoral or agricultural tribes. Tribes are much larger groups, and bring two new metrics: social rank and wealth. In human society, which by then relied almost entirely on visual cues, clothes, posture, jewelry, tattoos and scarification were used as markers for these metrics. There was still no need for “long-distance” pheromones or long-range MHC analysis, because in a typical tribe of a few hundred people, everyone was seen by everyone else over a reasonable period of time.
In summary, identifying odors generated by the MHC, and behavior-modifying odors such as pheromones evolved and became of vital importance in mammals that were solitary or which lived in closely-related family groups. Pheromones became less important, and finally counterproductive, in species that tended to aggregate themselves in clumps of up to a few hundred individuals. In human societies the ability to detect and discriminate among those odors at a distance was essentially lost (and in some cultures the odors themselves are often intentionally suppressed, as with perfume and frequent bathing) and were replaced by their visual equivalents, some or which were eventually suppressed by clothing.
Modern urban society is radically different from life in a tribe or hunting-gathering camp, especially for singles. In 2005, over 30% of the households in the United States were inhabited by “single” people: unmarried people, married people living apart from their spouses, and single-parent households with small children. Specifically, in the year 2000, the United States had a population of 281 million, of which 224 million, or about 80%, lived in cities or metropolitan area of 100,000 or more people. These people lived in 105 million households, of which 33 million, or 31%, were nonfamily households (up from 26% in 1980), and 27 million, or 26%, were one-person households (up from 23% in 1980). See U.S. Census Bureau, Statistical Abstract of the United States: 2001, (121st edition) Washington, D.C. 2001.
Unlike their ancestors in a tribe or camp, most people in the United States are now members of a free-ranging species, and, because they are ill-equipped for that role, have a very poor chance of meeting a compatible stranger, either for friendship or matrimony, without exposure to embarrassment or danger. The traditional mechanisms for singles to meet are attendance at churches and bars; in the first case, it is considered bad form to “go shopping” from church to church, and in the second, there is very little protection against predators and chemically impaired judgment, and no mechanism to filter the compatible from the incompatible.
Note that while this analysis is, for simplicity's sake, cast in terms of singles seeking singles, it is recognized that in urban areas, families which would like to establish social contact with other families suffer an even greater disadvantage because of their lower mobility and more complex selection criteria. In addition, purely inanimate objects, such as cranes and containers in a shipyard, can benefit from a mechanism that establishes mutual compatibility on a peer-to-peer level, without intervention of clerks or computers.
Many individuals have difficulty finding a mate. According to www.eHarmony.com, 21 million Americans spent $313 million dollars last year on Internet dating services. There are many other services similar to eHarmony.com, such as Match.com in the United States and Soulmates in the United Kingdom.
These are popular and profitable services. They not only find and filter acquaintance candidates, but also provide a sanctioned (though virtual) arena, like a church or small private party, in which strangers can meet without danger or embarrassment. They have the disadvantage of being cumbersome, time-consuming, and involving an elaborate contact ritual designed to avoid disappointment, embarrassment and danger; and the element of spontaneity, in which the best decisions are often made, is missing. See Gladwell, Malcolm, Blink: The Power of Thinking Without Thinking, Little, Brown & Co., 2005. They have the further disadvantage that the probability that couples they have matched will experience mutual attraction is quite low. See Gottlieb, Lori, “How do I Love Thee,” The Atlantic Monthly, Vol. 297, No. 2, pp 58-70 (March 2006) and Gamerman, Ellen, “Mism@tched.com.” The Wall Street Journal, Apr. 1, 2006, p 1.
There is also the disadvantage that online selection does not correspond well to the selection process that takes place in real-life acquaintance scenarios. Recent studies involving “Instant Dating” tests have shown that physical appearance is by far the most important consideration in the early stages of acquaintance. This is true for both genders (though more so for men). Therefore, an acquaintance process that does not quickly include face-to-face contact is somewhat artificial. Recent studies have also shown that individuals who select potential mates using static photographs have a greater-than-average chance of choosing a person to whom he or she will not be attracted. See Rubenstein, Adams J., “Variation in Perceived Attractiveness,” Psychological Science, Vol. 16, No. 10, pp 759-762 (2005) in which static images are shown to produce erroneous results, and Jones, B. C., et al., “Menstrual cycle, pregnancy and oral contraceptive use alter attraction to apparent health in faces,” Proceedings of the Royal Society B 273, pp 247-254 (2005).
Since it does not appear that natural pheromones and odors are greatly effective in helping men and women find each other, it would be extremely helpful if some type of man-made device could help enable people to find friends or mates based on specific criteria, retaining some of the precision and safety of the online dating sites, while maintaining the efficiency and naturalness of the church and the bar. It would also help to avoid some of the abusive and demeaning behavior now invading the dating process. See Netburn, Deborah, “Danger: Pickup Artists Ahead,” Los Angeles Times, Wednesday, Aug. 10, 2005, p. E1.
The development of such a device or system would constitute a major technological advance, and would satisfy long-felt needs and aspirations of the Internet dating industry and of Humanity in general.